The central hypothesis of this proposal is that specific temporal and spatial patterns of matrix metalloproteinase (MMP) and TIMP expression occur during wound repair and that alterations in these patterns may result in abnormal or chronic wound healing. A panel of riboprobes, antisera and functional assays to detect and quantitate the MMPs and TIMP at the mRNA, protein and functional level have been validated for use in both human and porcine tissue studies. The data will be evaluated in the context of histological and morphometric assessments of the wound bed. Three approaches will be used to establish the role of the MMPs and TIMP in wound repair. Specific Aim 1 seeks to establish the pattern of MMP and TIMP expression in non-healing human leg ulcers and to determine any changes in this pattern induced by the application of 3 prototypical wound care treatments including simple dressing, occlusion and epidermal pinch grafting. Functional assays of MMP and TIMP activities in wound tissues will be supplemented by immunohistochemical and in situ hybridization localizations of these proteins and their respective mRNAs. Specific Aim 2 extends these human studies to the porcine model of wound healing. Functional assays will quantitate MMP and TIMP activities in thermal and excisional wounds and their sites of synthesis will be determined by in situ hybridization. Changes in the expression patterns of these proteins will be determined in wounds altered by unfavorable (dry) and favorable (occlusive) wound environments and by 4 prototypic agents including glucocorticoids, betaFGF, TGFbeta and TNFalpha. Specific Aim 3 will explore the consequences of aberrant MMP and TIMP expression in transgenic mouse constructs. Keratin promoters will be used to provide site and situational control of the overexpression of these proteins. Superficial and partial-thickness injuries will be used to initiate wound repair and activate the MMPs. In situ, immunostaining and functional assays will document the production, distribution and activity of these proteins in the context of wound healing. Recombinant TIMP will be used to attenuate excess MMP activity and further establish the specificity of the role(s) of MMPs in this process.